YouTube has instituted a face blurring technology to allow those posting videos on the site to protect the identity of people in their clips, when need be. The company suggests that it's making this move to protect those shown in news and human rights footage.
That said, the feature is also available to the guy who doesn't want to be identified as the mean-spirited and demonic person that set his friend's shoe on fire while he was sleeping.
How it works, is that once the user has selected the video that he wants to edit within YouTube's Video Enhancements tool, he can go to the Additional Features section, find the Blur Faces options, and click "Apply". A preview of the edited video will then be available. If the user finds it acceptable, he can save the new clip and decide whether or not to delete the original one.
YouTube notes, however, that "this is an emerging technology" and that it will sometimes have trouble detecting faces. Faces that are shot at some angles, are obstructed by something else, or are captured in certain lighting conditions, may not be able to be blurred - same goes for if the video is of poor quality.